Silicon L2,3 core absorption obtained at the buried Al/Si(111) interface

Silicon L2,3 absorption spectra are obtained by spatially resolved electron-energy-loss spectroscopy as a function of distance away from the buried Al/Si(111) interface. Within 0.6 nm, scattering below the bulk absorption threshold is observed, accompanied by changes in shape above the threshold. In silicon, where the core hole is well screened, these variations signify changes in the local density of states above and below the conduction-band edge on a scale of about 0.3 eV. The results are discussed within the framework of the metal-induced-gap-states model. © 1991 The American Physical Society.